This invention relates to a method and apparatus for carrying out operations on a pie chart.
Pie charts provide a visual picture of composition data and are widely used in data processing fields. In one common data-processing scenario, a pie chart is shown on a display screen and the operator is asked to select one of the slices of the chart. A computational process is then executed according to the selected slice.
In a prior-art method of selecting slices from a pie chart, the slices are distinguished by different colors or patterns, and depictions of buttons with corresponding colors or patterns are displayed. Using a pointing device such as a so-called mouse, the operator moves a cursor to the button matching the desired slice, then clicks the button (by pressing a physical button on the mouse, for example) to select the slice.
A problem with the prior-art method is that the buttons are displayed in an area separate from the pie chart itself, so the operator must take time to check the correspondence between button and slice, which is source of irritation and mistakes. A further problem is that the buttons take up extra space on the display screen. Display space is generally limited; to accommodate the buttons, the pie chart itself must be reduced in size, making it difficult to distinguish small slices. Moreover, limited space for displaying buttons may restrict the number of allowable slices in the pie chart.